The investigators hypothesize that hepcidin will be increased and erythropoietin decreased early after trauma and that resolution of anemia will not occur until late (28-31 days). By measuring time-dependent changes in hemoglobin, hepcidin, cytokine, and erythropoietin concentrations in trauma patients, the investigators can critically examine the inter-relationships to target potential therapeutic strategies for the treatment and amelioration of anemia in trauma and critical care.